Adjustment mechanism



7 March 10, 1959 J. F. WAHL rrAL ADJUSTMENT MECHANISM Filed July 5, [1955 J3 .78 7 30 gamma;

United States Patent Ofifice 2,877,364 ADJUSTMENT MECHANISM John F. Wahl and Leo J. Wahl, Sterling, Wahl Clipper Corporation, Sterling, tion of Illinois 11]., assignors to 111., a corpora- This invention relates to an adjustment mechanism, and particularly to an adjustment mechanism which permits an unlimited primary adjustment and only a limited secondary adjustment.

Many manufactured devices have an element which is subject to adjustment. In certain instances it is undesirable for an ultimate customer to be able to adjust such an element in an unlimited manner, although, of course, the manufacturer requires unlimited adjustment in fabrieating or testing the device.

An object of the invention, therefore, is to provide an adjustment mechanism of such character that the manufacturer has an unlimited range of adjustment but that the customer has only a limited range of adjustment.

The adjustment mechanism of the invention will have numerous applications. By way of example the mechanism is here illustrated and described in connection with an electromagnetic device such as an electric hair clipper.

An electric hair clipper of the type here shown includes an electromagnet and a cooperating armature enclosed in a casing. The armature has a resilient arm which is mounted on a fixed support such as a wall of the casing.

Devices of this character are operated from commercial power sources. As is well known, commercial power voltages vary throughout the country, and often there are periodic variations in the voltage of an individual power source. Therefore, it is customary to provide an adjustment on the clippers to compensate for such voltage variation. Such an adjustment often is called a voltage regulation adjustment, or, if the adjustment is of the screw type, simply a power screw.

Commercial voltages generally are rated at 110 or 115 volts. Because of operational variations the voltages of commercial power sources tend to vary over a range, for example 104126 volts. Therefore, it is desirable that the ultimate customer should be able to regulate the device for voltages falling within this range. However, it is undesirable for the customer to be able to adjust beyond this range because a severe maladjustment condition may result, and it may be diflicult or impossible for the customer to correct the situation.

The present adjustment, as here illustrated, establishes a proper, predetermined rest position of an armature in relation to the core of an electromagnet. The proper, predetermined rest position of the armature is such that when the armature is vibrating under available voltage conditions, the armature just fails to impinge against the core.

If the available voltage should increase in value, the armature would, of course, strike the core. The adjustment mechanism permits the rest position of the armature to be moved slightly farther away from the core in order to restore proper operation.

Conversely, if the available voltage is low, the adjustment mechanism is used to move the rest position of the armature closer to the core, thereby preserving the desired clearance between armature and core.

A device of this character operates with maximum efiiwhich telescopes the end of 2,877,364 Patented Mar. 10, 9

ciency when the clearance between the armature and core under dynamic conditions is a minimum. The adjustment mechanism, of course, permits this minimum clearance to be set in response to any available voltage within the anticipated range.

Other objects, advantages and details of the invention will be apparent as the description proceeds, reference being had to the accompanying drawing wherein two forms of the invention are shown. It will be understood that the description and drawing are illustrative only and that the scope of the invention is to be measured by the appended claims.

In the drawing:

Fig. l is a plan view of an electric hair clipper embodying the invention, the cover of the clipper casing being removed for clarity;

Fig. 2 is a plan view of one form nism embodying the invention;

Fig. 3 is a sectional view on line 33 of Fig. 2;

Fig. 4 is a sectional view on irregular line 44 of Fig. 3;

Fig. 5 is a plan view of another form of adjustment mechanism embodying the invention;

Fig. 6 is a sectional view on line 66 of Fig. 5, and

Fig. 7 is a sectional view on irregular line 77 of Fig. 6.

Referring to the drawing, the illustrated electric clipper includes a casing 10 which houses an electromagnet 11 having a core including pole faces 12, 13 and 14. Also housed within casing 10 is an armature 18 having an armature arm 19. The latter, as here shown, is secured to wall 20 of casing 10 by means of screws 21.

Armature arm 19 extends longitudinally between the aforesaid casing wall 20 and opposite casing wall 23, as shown in Fig. 1. The static, rest, or center position of armature arm 19, and consequently of armature 18, is determined by a pair of compression springs 25 and 26. The former extends between armature arm 19 and easing wall 23 while the latter extends between arm 19 and the adjustment mechanism of the invention. This mechanism, generally designated 30 in Fig. 1, is associated with casing wall 20. As will be seen from Fig. l, compressing the springs 2526 by means of adjustment mechanism 30 moves the static, rest, or center position of armature 18 closer to the pole faces of core 11 while relaxing the springs moves this armature position farther from the pole faces.

Speaking more broadly, armature arm 19 is an element on one side of a wall which is capable of being adjusted into different positions, and adjustment mechanism 30 cooperates therewith and with spring 26 to provide desired adjustment. As will be seen, mechanism 30 permits unlimited adjustment under certain circumstances and limited adjustment under other circumstances.

For convenience of description terms denoting primary and secondary adjustments will be used. Primary adjustment refers to that unlimited range of adjustment which is available to the manufacturer while secondary adjustment refers to the limited range of adjustment which the mechanism makes available to a customer.

Referring to Figs. 2, 3 30 is carried by wall 20. 26 (Fig. 3) which in turn of adjustment mechaand 4, adjustment mechanism Mechanism 30 engages spring engages armature arm 19. Adjustment mechanism 30 includes a primary adjusting means 32 which is in contacting relation with wall 20. As here shown, wall 20 is provided with a threaded aperture 33 which receives primary adjusting means 32, the latter having external cooperating threads. Primary adjusting means 32 may have a boss 34 at its inner end spring 26 and provides extra material for a holding screw presently to be mentioned.

Primary adjusting means 32 is subject to rotation which provides in-and-out movement with respect to wall 20. This in-and-out movement, of course, imparts the desired adjustment to spring 26 and armature arm 19. Primary adjustment means 32 is subject to unlimited in-and-out movement; it is the part of the adjustment mechanism which the manufacturer actuates in order to make an adjustment which falls within the limited adjusting range to be made available to the customer.

A secondary adjusting means 35 operable from the exterior of wall 20, or from the side of the wall opposite spring 26, is carried by primary adjusting means 32. Secondary adjusting means 35 is capable of imparting movement to primary means 32, as will be seen.

As shown in Figs. 3 and 4, primary means 32 has an axial bore 37 containing splines 38, best shown in Fig. 4, at its lower end. Secondary means 35 has a reduced portion 40 which enters bore 37, reduced portion 49 having splines 41 at its lower end. Splines 38 and 41 interlock so that primary and secondary means 32 and 35 may rotate as one.

A holding screw 43, countersunk in secondary means 35, threads into primary means 32 to hold the two means together.

The upper portion of secondary means 35 may be provided with a slot 45 so a screw driver can be used for making the primary adjustment of primary means 32. Alternatively, a splined tool insertable in the bore of primary means 32 may be used to make the primary adjustment before secondary means 35 has been assembled.

Suitable means is provided to limit the operation of secondary adjusting means 35. As shown in Figs. 2 and 4, this means includes a pin 47 which extends outwardly from wall 20. Pin 47 cooperates with stop faces 48 and 49 (Fig. 2) of a stop 50. The latter is an enlarged head at the upper portion of secondary means 35. With this arrangement, rotation of secondary adjusting means 35' is limited to something less than one revolution. In the clipper example given, this is a sutficient adjustment to enable the customer to adjust for voltages falling in the 104-126 volts range.

The form of the invention from the form just described in several respects. Primary adjusting means 55 has a central bore 56 (Fig. 6) which has a maximum diameter on a plane 57 between its ends. Bore 56 tapers inwardly in both directions from plane 57, the diameter at the inner end of the bore being slightly smaller than that at the outer end of the bore. A portion of the walls of the bore are serrated as shown at 58. The portion of primary means 55 containing bore 56 is hereinafter referred to as a female portion. Secondary adjusting means 60 has a reduced male portion 61 which is received within the aforesaid female portion of primary means 55. Male portion 61 is tapered to correspend in shape with bore 56 and it is provided with external serrations which cooperate with the serrations 58 of primary means 55.

One or both of the primary and secondary adjusting means 55 and 60 is made of resilient plastic material so that the female and male portions thereof may telescope together with snap action and resist separation. The serrations, of course, enable the two portions to turn together. The two tapers on male portion 61 and bore 56 respectively aid in assembly and cooperate to hold the two means together.

The operation-limiting means in this form of the invention, like in the other one, comprises a pin and stop arrangement. A pin 64 extends outwardly from wall 20 and engages a stop forming part of secondary means 60. As here shown, an arcuate recess 65 is provided in the lower surface of the upper portion of secondary means 60, the pin 64 entering the recess. The recess ends 66 and 67 are faces of a stop which limits the angular movement of secondary adjusting means 60.

shown in Figs. 7 differs Although the pin is shown in wall 20 and the recess is shown in secondary means 60, it will be understood that the pin may be carried by secondary means 60 and the recess provided in wall 20, if desired.

Still another form of operation-limiting means which can be used with the Fig. 5-7 arrangement is that shown in Fig. 2. It is the one that is used in applicants present commercial product. In this case the head of secondary means 60 has a segmental portion of increased radius to provide stops corresponding to faces 48 and 49 in Fig. 2. The head is countersunk in the exterior face of the casing wall, and the limit element corresponding to pin 47 is a boss on the wall of the countersunk recess. The faces of the segmental portion of increased radius engage the boss to limit the extent of the secondary adjustment range.

From the above description it is thought that the construction and advantages of our invention will be readily apparent to those skilled in the art. Various changes in detail may be made without departing from the spirit or losing the advantages of the invention.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is:

1. Mechanism capable of providing primary and secondary adjustment through a wall, comprising a primary adjusting element having screw-threaded engagement with a screw-threaded hole in said wall so as to project therethrough to engage an element to be adjusted located on the inner side of said wall, said screwthreaded primary adjusting element having means whereby it may be engaged by a tool from the outer side of said wall to effect primary adjustment thereof and of the element to be adjusted, a secondary adjusting element, said primary and secondary elements having cooperating telescoping engaging means whereby said secondary element upon being placed into driving relationship with said primary element is adapted to effect secondary adjustment thereof from the outer face of said Wall, means on said secondary element cooperating with means on said wall to limit the rotative movement of said elements, and cooperating means aforesaid on said wall.

2. Mechanism capable of providing primary and secondary adjustment through a wall, comprising a primary adjusting element having screw-threaded engage: ment with a screw-threaded hole in said wall so as to project therethrough to engage an element to be adjusted located on the inner side of said wall, said screwthreaded primary adjusting element having a bore and means therein whereby it may be engaged by a tool from the outer side of said wall to effect primary adjustment thereof and of the element to be adjusted, a secondary adjusting element, said primary and secondary elements having cooperating telescoping engaging means whereby said secondary element upon being placed into driving relationship with said primary element is adapted to effect secondary adjustment thereof from the outer face of said wall, means on said secondary element cooperate ing with means on said Wall to limit the rotative move ment of said elements, and cooperating means aforesaid on said Wall.

3. Mechanism capable of providing primary and secondary adjustment through a wall, comprising a primary adjusting element having screw-threaded engagement with a screw-threaded hole in said Wall so as to project therethrough to engage an element to be adjusted located on the inner side of said wall, said screwthreaded primary adjusting element having a bore and and means therein whereby it may be engaged by a tool from the outer side of said wall to effect primary adjustment thereof and of the element to be adjusted, a secondary adjusting element, said primary and secondary elements having cooperating telescoping engaging means whereby said secondary element upon being placed into driving relationship with said primary element is adapted to effect secondary adjustment thereof from the outer face of said wall, means on said secondary element cooperating with means on said wall to limit the rotative movement of said elements, cooperating means aforesaid on said wall, and screwthreaded means to secure said primary and secondary elements together.

4. Mechanism capable of providing primary and secondary adjustment through a wall, comprising a primary adjusting element having screw-threaded engagement with a screw-threaded hole in said wall so as to project therethrough to engage an element to be adjusted located on the inner side of said wall, said screwthreaded primary adjusting element having means whereby it may be engaged by a tool from the outer side of said wall to effect primary adjustment thereof and of the element to be adjusted, a secondary adjusting element, said primary and secondary elements having cooperating splined telescoping engaging means whereby said secondmy element upon being placed into driving relationship with said primary element is adapted to effect secondary adjustment thereof from the outer face of said wall,

means on said secondary element cooperating with means on said wall to limit the elements, and cooperating rotative movement of said means aforesaid on said wall.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS Australia May 12, 1955 

